The Louisiana Democrat. [volume] (Alexandria, La.) 1845-1918, 1887-05-18
HOW CREAM RISES
Many Points That Are But Imperfectly
Understood by Most Dairymen.

The secret OF raising cream CONSISTS
in suddenly cooling the milk. In
round numbers we are told that milk
is eighty-seven per cent. water, four
per cent. sugar, and the same quantity
of butter fats. The fat is the part
which we wish to separate from the
milk, to manufacture into butter.
Milk is a little heavier than water,
probably on account of the sugar it
contains. 1t also heats and cools much
slower than water, hence it is what
our scientific friends call a "bad con-
ductor."
If milk, which is composed so large.
" of water, heats and cools more
slowly than water, it can only be &C.
counted for by the fact that the re-
naming thirteen per cent, which con-
tains the butter fat, holds heat,
or keeps the milk from cooling
as soon as water, under pre-
cisely similar conditions. We know
that milk or water will shrink in cool
ing, at least we know that the power
of steam is due to the expansion Of
water caused by heat. I find that milk
contracts so it weighs about half an
ounce more to the gallon at forty-eight
degrees than at niuety-eight degrees.
To prove this last statement that
water is a better conductor of heat
than milk, put one hand into pail of
water at a Temperature of thirty-two
degrees, and hold the other in pail OF
milk, of the same temperature. You
will find that the hand in the water
will feel sensation of cold before the
one in the milk.
Take can of milk eight and hall
inches in diameter, and twenty inches
deep. Place this in vessel of water
of the same depth, which contains as
much water as the other does of milk
The temperature of the milk being
ninety-eight degrees, and of the
water foty-eight degrees. In a
short time the thermometer
| Will show us that the milk ana Inc
water are both of the same temper.
allure, or seventy-three degrees, the
water having taken part Of the heat
from the milk, thereby increasing its
own temperature, and decreasing that
of the milk. If can of milk were
placed in large quantity of water, as
in we'll, there would be so much more
water than milk that the milk would
be reduced to the temperature of the
water without sensibly decreasing the
temperature Of the water. 1t would be
found that the temperature of the milk
had not only been decreased, but that
the cream had risen to the surface, il
the milk had been left long enough in
the water. WhyP Water on cooling
shrinks, and becomes denser-that is,
weighs more, cubic foot for foot
Now, when the milk is placed in
the cold water it is gradually cooled,
but it does not cool evenly. AS said
before, eighty-seyen per cent. of the
milk is water, and this cools more
rapidly than the other thirteen pei
cent of fats, etc.. and consequently
shrinks and becomes heavier. If we
put two liquids in vessel together
the heavier one will sink to the bottom
and the lighter one rise to the top
just so the watery part of the milk set
ties to the bottom of the can, and the
lighter part, which does not cool 81
, rapidly as the water, and therefore
shrinks slower, rises to the top. If thi
reasoning is true, it is very importan
that it be well understood, so that tn.
underlying principle may be taken adj
vantage of by the different farmers
whose conveniences for their work vary
so widely.
There is one point which must not b.
overlooked in the above reasoning
We have said that cooling milk cause!
! it to shrink and become heavier, bu
the temperature must never be below
thirty-nine degrees. If l have not for
gotten the valuable lesson that water
shrinks as it cools to thirty-nine de
grees, and then begins to expand i
cooled further. Cooling below thirty
nine degrees is, therefore, detrimental
I have made this Il study many years
and came to the conclusion here givel
long ago, and acted upon it. This stud,
has been to perfect the system of cream
raising that can be done on tn
farm. One that the farm provide
for the year round without even tn
aid of ice, though ice is a valuable hell
in hot weather. The temperature o
deep wells is about forty-eight. ant
this will answer very satisfactorily fol
cream raising, provided we do not de
lay in straining and setting the cans
In this well water, and do not allow
the water to warm up, which it viii
surely do if there is not large enough
| quantity of it. or if it is not Otter
changed. The water will conduct thu
heat out of the milk into itself just a.
surely as it will conduct the heat on
of n red-hot iron placed in it. G.
Curtis, in Prairie Farmer.